Key result
Nifedipine depressed stress maintenance and V0 without affecting stress development or MLC phosphorylation, whereas BAY-K 8644 produced contractions with low V0 and basal/low MLC phosphorylation.
Population
Swine carotid medial fibers
Comparison
Nifedipine or BAY-K 8644 during contraction with… vs Contraction with 110 mM KCl alone
Design
Preclinical
Authors
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Animal data warrant caution extrapolating to human vascular tone; extends mechanistic insight into calcium-dependent cross-bridge regulation but requires validation.
Different mechanisms of cellular calcium increase and its limitations impact differently on regulatory processes of contraction and cross bridge behavior in smooth muscle.
Moreland et al. (1987) studied this question. Nifedipine and BAY-K 8644 vs. 110 mM KCl was evaluated on Stress development, stress maintenance, myosin light chain (MLC) phosphorylation, and maximum shortening velocity (V0). Nifedipine depressed stress maintenance and V0 without affecting stress development or MLC phosphorylation, whereas BAY-K 8644 produced contractions with low V0 and basal/low MLC phosphorylation.
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